(1) If the car sends four people to the examination room and then returns to the fault location to pick up the other four people, please calculate whether you can arrive at the examination room before the deadline for entering the examination room.
(2) The teacher who led the team put forward a plan: firstly, four people will be sent to the examination room by car, and the other four will walk to the examination room at the same time. After the bus arrives at the examination room, it will return and then pick up four people who walked to the examination room. Please illustrate the feasibility of the plan through calculation.
(3) How long does it take for all students and teachers to arrive at the examination room?
Analysis: (1) Because the car broke down at a distance of 15km from the examination room, the distance traveled by another car to send its personnel to the city and then back should be 15x3. If calculated according to the known conditions, it can be judged whether to arrive at the examination room before the time of entering the examination room.
(2) Assuming that the car will send four people to arrive and return, and four other hikers are met after X hours, then the car and hikers are meeting, and the problem can be solved by the distance equation;
(3) Send four people by car, and the other four people will walk at the same time. Take the car to a place and let four people get off and walk. Eight people go to the examination room at the same time, which takes the least time. If the car leaves for x hours and goes back to pick up four other people, then the distance traveled by the car is 60x, and the remaining distance is (15-60x), then the people at this time.
[( 15-60x)÷ 15] hours, while the other four people left first 15x, leaving (15-60x) kilometers, which requires (15-60x) 20.
Solution: (1) The required time is: 15×3÷60×60=45 minutes.
∵45>42,
Can't arrive at the examination room before the time of entering the examination room.